Cell-specific delivery of cytotoxic drugs via passive and active targeting is an important objective in order to improve cancer chemotherapy. Successful targeting may be accomplished if the targeting vehicle has appropriate dimensions for tumor localization via the enhanced permeability and retention (EPR) effect, and binds with high affinity to an antigen that is specifically expressed by targeted cells. The drug complex should also be stable, such that the drug is retained in the complex during targeting, which may take several hours, but released from the complex after binding to the targeted cell. Drug delivery should also be efficient, releasing multiple drugs for each successfully targeted complex. There remains a need for new targeted drug delivery approaches that display stability with high payload delivery in order to accomplish these goals.